/**
 * Copyright (c) 2015-present, Facebook, Inc.
 *
 * This source code is licensed under the MIT license found in the
 * LICENSE file in the root directory of this source tree.
 */

#import "RCTSafeAreaView.h"

#import <React/RCTBridge.h>
#import <React/RCTUIManager.h>

#import "RCTSafeAreaViewLocalData.h"

@implementation RCTSafeAreaView {
  __weak RCTBridge *_bridge;
  UIEdgeInsets _currentSafeAreaInsets;
}

- (instancetype)initWithBridge:(RCTBridge *)bridge
{
  if (self = [super initWithFrame:CGRectZero]) {
    _bridge = bridge;
  }

  return self;
}

RCT_NOT_IMPLEMENTED(- (instancetype)initWithCoder:(NSCoder *)decoder)
RCT_NOT_IMPLEMENTED(- (instancetype)initWithFrame:(CGRect)frame)

static BOOL UIEdgeInsetsEqualToEdgeInsetsWithThreshold(UIEdgeInsets insets1, UIEdgeInsets insets2, CGFloat threshold) {
  return
    ABS(insets1.left - insets2.left) <= threshold &&
    ABS(insets1.right - insets2.right) <= threshold &&
    ABS(insets1.top - insets2.top) <= threshold &&
    ABS(insets1.bottom - insets2.bottom) <= threshold;
}

#if defined(__IPHONE_OS_VERSION_MAX_ALLOWED) && __IPHONE_OS_VERSION_MAX_ALLOWED >= 110000 /* __IPHONE_11_0 */

- (void)safeAreaInsetsDidChange
{
  if (![self respondsToSelector:@selector(safeAreaInsets)]) {
    return;
  }

  [self setSafeAreaInsets:self.safeAreaInsets];
}

#endif

// Emulate safe area for iOS < 11
- (void)layoutSubviews
{
  [super layoutSubviews];
  if ([self respondsToSelector:@selector(safeAreaInsets)]) {
    return;
  }
  UIViewController* vc = self.reactViewController;
  if (!vc) {
    return;
  }
  CGFloat topLayoutOffset = vc.topLayoutGuide.length;
  CGFloat bottomLayoutOffset = vc.bottomLayoutGuide.length;
  CGRect safeArea = vc.view.bounds;
  safeArea.origin.y += topLayoutOffset;
  safeArea.size.height -= topLayoutOffset + bottomLayoutOffset;
  CGRect localSafeArea = [vc.view convertRect:safeArea toView:self];
  UIEdgeInsets safeAreaInsets = UIEdgeInsetsMake(0, 0, 0, 0);
  if (CGRectGetMinY(localSafeArea) > CGRectGetMinY(self.bounds)) {
    safeAreaInsets.top = CGRectGetMinY(localSafeArea) - CGRectGetMinY(self.bounds);
  }
  if (CGRectGetMaxY(localSafeArea) < CGRectGetMaxY(self.bounds)) {
    safeAreaInsets.bottom = CGRectGetMaxY(self.bounds) - CGRectGetMaxY(localSafeArea);
  }

  [self setSafeAreaInsets:safeAreaInsets];
}

- (void)setSafeAreaInsets:(UIEdgeInsets)safeAreaInsets
{
  if (UIEdgeInsetsEqualToEdgeInsetsWithThreshold(safeAreaInsets, _currentSafeAreaInsets, 1.0 / RCTScreenScale())) {
    return;
  }

  _currentSafeAreaInsets = safeAreaInsets;

  RCTSafeAreaViewLocalData *localData = [[RCTSafeAreaViewLocalData alloc] initWithInsets:safeAreaInsets];
  [_bridge.uiManager setLocalData:localData forView:self];
}

@end
